Newly embattled Employment Minister Jason Kenney launched a torrid Twitter assault Wednesday after former Liberal leader Bob Rae said the temporary foreign workers program has its roots in “anti-immigration bias.”

The temporary foreign workers [TFW] “issue has roots in Reform’s anti-immigration bias — explosion in ‘temporary’ category is all about segregating and excluding,” Bob Rae wrote on Twitter Wednesday morning, sparking an avalanche of response.

“That’s obscene and beneath you,” Kenney, one of few remaining Conservative MPs who was originally elected as a Reform Party member, responded. “We’ve increased immigration to record levels, the highest per capita level in the developed world.”

Kenney then fired off a long series of tweets about Rae’s comments, heavy on facts about his government’s record on immigration.

“In parallel world of Harper Derangement Syndrome, the most pro-immigration [government] in modern CDN history has ‘anti-immigration bias,'” Kenney said in his final volley.

“The [number] of TFWs entering Canada has gone from .7% of workforce in 2006 to 1.1% of workforce in 2012. This is “anti-immigration?”

Rae, as of about noon Wednesday, did not respond on Twitter.

Kenney, a popular former Immigration minister who has long been seen as a potential successor to Prime Minister Stephen Harper, has come under the most sustained pressure of his career in recent weeks over abuse allegations with the temporary foreign workers program.

There have been a number of allegations, most involving fast-food restaurants, of employers taking advantage of the temporary foreign workers program by replacing Canadians with cheaper labour.

Kenney has hinted tougher regulations coming in the future but has yet to offer specifics in response to the latest controversy.

“If and when there are abuses, we act clearly and quickly,” he said on Monday, after placing a temporary ban on restaurants from using the TFW program.

“We are about to come out with another phase of further reforms to ensure that Canadians always and everywhere get the first crack at available jobs, and that the program is only used as a limited and last resort by employers.”

The non-partisan C.D. Howe Institute recently released a study that said the increase of temporary foreign workers over the past 10 years — from 110,000 to 338,000 — has worsened the employment rate in B.C. and Alberta.

Hundreds of Canadian businesses — including government departments — employ temporary foreign workers. The program was intended to target highly skilled workers, not menial labour.

TFW issue has roots in Reform's anti-immigration bias – explosion in "temporary" category is all about segregating and excluding. #cdnpoili

NDP Leader Tom Mulcair took shots at the Conservative government — and in particular, Minister Kenney — earlier this week, suggesting the opposition figures there is political ground to be made on the file.

“The minister has been responsible for the temporary foreign worker program for the past six years,” Mulcair said during question period.

Mulcair said that unlike Harper, Kenney has never figured out that some companies have “the intention of never having them be permanent and moving the whole workforce back to another country at the end of a job?”